Fabric softener composition

ABSTRACT

The invention relates to a fabric softener composition comprising an aqueous phase comprising a cationic softener and a hydrophobic phase comprising a fragrance. The composition should be shaken prior to use for adapting a dispersion which separates into an aqueous phase and a hydrophobic phase after use. The composition may be used as fabric softener to give a pleasant feet, and to prolong the release of fragrance on fabrics up to 7 days.

The present invention relates to fabric softener compositions, in particular to fabric softener compositions comprising an aqueous phase and a hydrophobic phase.

Fabric softeners for domestic use are primarily designed to give a pleasant feel to fabrics, to impart freshness or a pleasant smell, and to control the static electricity that impairs the comfort of handling and wearing clothes. They are generally aqueous dispersions containing a cationic softener as an active material. Fabric softener composition usually have a pH value below 4 due to the active material, i.e. the cationic softener, whereas detergents which contain mostly anionic surfactants as active ingredient have a pH value above 5, preferably above 7, more preferably about 9 to 10, depending on the application, e.g. fabric or skin.

A known fabric softener composition is disclosed in WO 97/16516 comprising a cationic fabric softener, a fragrance, a non-ionic surfactant, a water-soluble ionisable inorganic salt and water. The fabric softener composition is in the form of an aqueous phase with discrete hydrophobic particles dispersed substantially uniformly throughout the aqueous phase. A problem with aqueous dispersions of this type is that the fragrance is mixed intimately with the other ingredients. Some of the ingredients, e.g. the cationic softener, tend to degrade fragrance over time. Also, the degradation of the fragrance is promoted by the aggressive acidic media, pH<4, contained in such fabric softener compositions.

A multiple-phase fabric care composition comprising visually distinct phases is disclosed in WO01/98450. Whereas fabric care agents including perfume are disclosed, the reference provides no teaching to the effect that perfume and cationic softener should be contained in separate phases.

It has now been found that a fabric softener composition comprising fragrance and cationic softener can be produced which is substantially free of the problems associated with degradation of fragrance material during storage in aggressive media.

Accordingly, the invention provides in one of its aspects a fabric softener composition having an upper hydrophobic phase comprising a fragrance and a lower aqueous phase comprising a cationic softener.

Compositions according to the present invention are possessed of numerous advantages. By means of providing two distinct phases, the fragrance is separated from aggressive media such as the cationic softener and accordingly, from the acidic aqueous phase which at a pH value below 4, particularly between 3 and 1, more particularly between 2.5 and 1, may act to degrade the fragrance, and as such, its effect is much longer lasting compared with fragrances employed in aqueous dispersion systems.

Further, given that substantially all of the fragrance is located in a hydrophobic phase which sits on the top of the aqueous phase, the user is presented with an enhanced burst of fragrance upon opening a package, e.g. a bottle, containing a composition according to the present invention compared with aqueous dispersion systems wherein the fragrance is dispersed throughout the composition in a less concentrated manner.

Other advantages of the present invention will be apparent from the following description and examples.

As the composition is provided as a two-phase system, it should be shaken prior to use to ensure good mixing of all the ingredients. However, because of the problem of fragrance degradation it is desirable that after use, the composition re-establishes its two-phase form as quickly as possible, and preferably separation into the distinct phases occurs within about 10 to about 40 minutes after agitation.

It has been found that certain softeners promote rapid phase separation. Softeners for use in a composition according to the present invention may be selected from cationic softeners, more particular from the group of cationic quaternary ammonium salts; ester-linked quaternary ammonium compounds; imidazolinium salts; and amido amine salts. Particular examples of these cationic softeners are described in more details below.

Quaternary ammonium compounds useful in the present invention may be selected from compounds of the formula:

wherein each of R¹ and R² is independently selected from a hydrocarbon residue having from 8 to 28, preferably 2 to 24 carbon atoms; R³ and R⁴ represent hydrocarbon residues containing from 1 to 4 carbon atoms; and X⁻ is an anion, which can be any suitable softener-compatible anion, for example, halide (preferably chloride or bromide), methylsulfate, ethylsulfate, formate, sulfate, nitrate, acetate and the like. Representative examples of these quaternary ammonium compounds include ditallow dimethyl ammonium chloride, ditallow dimethyl ammonium methyl sulphate, dihexadecyl dimethyl ammonium chloride, di(hydrogenated tallow) dimethyl ammonium methyl sulphate, dihexadecyl diethyl ammonium chloride and di(coconut oil alkyl) dimethyl ammonium chloride.

Suitable materials also include dialkyl ethoxyl methyl ammonium methosulphate based on soft fatty acids, dialkyl ethoxyl methyl ammonium methosulphate based on hard fatty acids, and compounds in which R³ and R⁴ represent methyl, R² is C₁₃₋₁₅ hydrocarbon group, R³ is CH₂CH₂OCOR⁵ where R⁵ is stearyl, and X⁻ is methylsulphate anion.

Particular preferred cationic softener useful in the composition according to the invention can be an ester-linked quaternary ammonium compound represented by the formula:

wherein each R⁶ group is independently selected from C₁₋₆ hydrocarbon residue, such as alkyl, alkenyl or hydroxyalkyl groups; and wherein each R⁷ group is independently selected from C₈₋₂₈ linear or branched hydrocarbon residue, such as alkyl or alkenyl groups;

T is

wherein R⁸ represents hydrogen, methyl, or ethyl;

n is an integer from 0-5 and m is an integer from 1-4;

and X⁻ is an anion as defined as above.

A preferred material of ester-linked quaternary ammonium compound is that of formula:

wherein each R⁹ is a linear or branched alkyl or alkenyl chain comprising at least 11 atoms such as tallow and X⁻ is an anion as defined above and, in particular, is methylsulfate. A compound having R¹¹ is tallow and X⁻ is methylsulphate anion is available from Witco under the trade name Rewoquat® WE 18. Another example of this type of material is a compound wherein R¹¹ is of partially hardened tallow and X⁻ is methylsulphate anion.

Another preferred class of cationic softener containing two ester groups is represented by the formula:

wherein R¹⁰ is a linear or branched alkyl or alkenyl residue such as tallow, or partially hardened tallow and X⁻ is an anion as herein above defined and in particular chloride or methylsulphate.

Other ester-linked quaternary ammonium compounds, which may be used in the compositions of the present invention, are those of the formula:

wherein each R¹¹ is independently selected from C₁₋₄ hydrocarbon residue, such as alkyl, alkenyl or hydroxyalkyl groups; and each R¹² is independently selected from C₈₋₂₈ linear or branched hydrocarbon residue, such as alkyl and alkenyl groups;

T has the meaning as described above;

n is an integer of from 0-5 and m is an integer from 1-4;

X⁻ is an anion as defined above, preferably selected from halide, methylsulphate and ethylsulphate.

The most preferred class of cationic softener is a biodegradable fatty ester quaternary ammonium compound of formula:

wherein each R¹³ independently represents an aliphatic hydrocarbon residue having from 8 to 22 carbon atoms; R¹⁴ represents (CH₂)_(s)R¹⁶ where R¹⁶ represents an alkoxy carbonyl residue containing from 8 to 22 carbon atoms, benzyl, phenyl, C₁-C₄-alkyl substituted phenyl, OH or H; R¹⁵ represents (CH₂)_(t)R¹⁷ where R¹⁷ represents benzyl, phenyl, C₁-C₄-alkyl substituted phenyl, OH or H; q,r,s and t each independently, represent a number from 1 to 3; and X⁻ is an anion as defined above, and the symbol “a” represents the ionic valance of the anion.

Other preferred cationic softener are the hydrocarbylimidazolinium salts having the formula:

wherein R¹⁸ is a hydrocarbon residue containing from 1 to 4, preferably 1 or 2 carbon atoms; R²¹ is a hydrocarbon residue containing from 8 to 25 carbon atoms; R¹⁹ is a linear or branched hydrocarbon residue containing from 8 to 25 carbon atoms; R²⁰ is hydrogen or a hydrocarbon residue containing from 1 to 4 carbon atoms; and X⁻ is an anion as defined above, and in particular a halide, methylsulphate or ethylsulphate.

Preferred imidazolinium salts include 1-methyl-1-(tallowylamido-) ethyl-2-tallowyl-4,5-dihydroimidazolinium methosulphate and 1-methyl-1-(palmitoylamido) ethyl-2-octadecyl-4,5-dihydroimidazolinium chloride. Other useful imidazolinium materials are 2-heptadecyl-1-methyl-1-(2-stearylamido)-ethyl-imidazolinium chloride and 2-lauryl-1-hydroxyethyl-1-oleyl-imidazolinium chloride.

Another class of preferred cationic softener are amido amine compounds of the formula:

wherein R²² and R²³ independently represent C₁₂ to C₃₀ aliphatic hydrocarbon residues; R²⁴ represents (CH₂CH₂O)_(p)H, CH₃ or H; n=1 to 5; m=1 to 5; and p=1 to 10.

However, of the cationic softener mentioned above, it has been found that the ester-linked quaternary ammonium compounds show a reduced tendency as emulsifying agents compared with the other classes of cationic softener and thereby promote rapid separation of the composition into two distinct phases. Other advantages of these softeners are the good biodegradibility and their efficient softening results. Because of the aforementioned advantages, ester-linked quaternary ammonium compounds are preferred. Most preferred cationic softeners according to the present invention include Rewoquate® WE18 and Rewoquate® WE15.

Notwithstanding that the softener referred to hereinabove permit phase-separation within an acceptable time period, nevertheless they are surfactants and it is in the nature of surfactants to resist, to a certain extent, phase-separation and as such it is preferred to use as little cationic softener as possible. However, the cationic softener is needed to impart softness to fabrics and so one has to strike a balance between the need for rapid phase separation and the competitive need for acceptable fabric softness. It is within the realm of routine experimentation for the skilled person to find an appropriate balance having regard to these competing factors. However, it is preferred to use in the composition according to the present invention about 1% to about 18% (w/w) of a cationic softener, preferably 2% to 13%, more preferably 5% to 10% (w/w).

Non-ionic surfactants are used in fabric softener compositions of the prior art for example, in combination with cationic softeners. However, we have found that non-ionic surfactants promote emulsification to an extent that phase separation is not quickly established using these materials. Accordingly, it is preferred to avoid the use of non-ionic surfactants in compositions of the present invention.

It has been found that by adding salts to the aqueous phase the speed of phase separation may also be influenced. Thus, the aqueous phase may comprise organic salts, such as alkali citrates and inorganic salts, for example sodium chloride and calcium chloride. Furthermore, whereas aqueous phase viscosity may drift over time, the provision of salts in this phase act to stabilise the viscosity. This has the advantage that the composition has a substantially constant quality over time. Compositions according to the present invention preferably comprise up to 2% (w/w), more preferably up to 1% , most preferably up to 0.5% salts.

Preferred inorganic salts include alkali and alkaline earth halides, e.g. Mg-, Na-, Li-, Ca-, K-, and Al-halides, alkali and alkaline earth nitrates, sulphates, phosphates and silicates; including hydrates of these salts, and mixtures thereof.

Preferred organic salts include alkali and alkaline earth salts of the carboxylic acids including formate, acetate, propionate, pelargonate, citrate, gluconate and lactate aromatic acids.

Other excipients optionally present in the aqueous phase are anti-foaming agents, thickeners, fluorescent whitening agents, optical brightening agents, anti-wrinkling agents, anti-shrinking agents, sunscreens, colour care agents, colorants, ironing aids.

The fabric softener composition according to the present invention comprise up to 8% (w/w) of these other excipients, preferably from 2% to 5% (w/w).

The hydrophobic phase according to the present of the invention comprises an oil and fragrance.

To achieve a fast separation after agitation of the composition according to the present invention such oils are preferred wherein the HLB (hydrophilic-lipophilic balance) is below 5, more preferably between 4 and 1. The oil may be a hydrocarbon oil, for example a mixture of hydrocarbon oils obtained from petroleum, in particular petroleum jelly or for example Isopar® produced by Exxon, in particular Isopar® L, Isopar® M or Isopar® H. Other preferred oils are silicone oils such as dimethicone polysiloxane or Tegopren®; or ester oil such as isopropylmyristate, ethylhexyl laurate, isopropyl laurate, octyl adipate and ethylhexyl cocoate. Mixtures of ester oil, hydrocarbon oil and silicone oil may also be used. Because of environmental reasons biodegradable oils are preferred. Accordingly, most preferred oils are esters oils, for example isopropylmyristate, isopropylpalmitate, neopentyl glycol diethylhexanoate, glycerol trioleate or glyceryl triheptanoate. To avoid alteration of the characteristic of the fragrance by the oil, such oils are preferred, which have a low evaporation rate.

The fabric softener composition according to the present invention comprises 1% to 50% (w/w) of the hydrophobic phase, preferably 3% to 20% (w/w), and most preferred 5% to 12% (w/w).

In addition to the role of providing a supporting phase for the fragrance which is separate from the aggressive media contained in the aqueous phase, the oil may also treat a fabric to impart softness thereto. Accordingly, the presence of the oil may have the beneficial effect of permitting the use of less cationic softener which is relatively expensive compared with the oil.

Further, the oil may coat the fragrance, such that when the composition is applied to a fabric it tends to promote prolonged release of fragrance and so increasing the substantivity of the fragrance on the fabric, for example preferred compositions according to the invention may impart fragrance to a fabric for up to 7 days after treatment. It was found that the rinse loss of the fragrance during the rinse cycle and/or the fragrance lost during the tumble drying process is much lower compared with aqueous dispersion fabric softeners. On dry fabrics a 3-5 time stronger fragrance, measured by headspace, can be achieved compared with conventional aqueous dispersion fabric softeners. The headspace analysis is described in the Journal of Agriculture and Food Chemistry, Vol. 19, No. 6 (1971), page 1049-1056.

The composition according to the present invention may contain all kinds of fragrances of natural and/or synthetic origin, for example geraniol, citronellyl acetate, d-limonene, orange terpenes and vanilline. The composition comprises one fragrance or a mixture of fragrances. However, to limit the migration of fragrance from the hydrophobic phase to the aqueous phase water soluble fragrances are preferably to be avoided. The aqueous solubility of a fragrance is conventionally measured using a number of different procedures such as for example the procedure disclosed in Etzweiler et al., Analytical Chemistry, Vol. 67, No.3 (1995) expressed in grams per gram of solution of the fragrance; or it may be determined from the partition coefficient of the fragrance between octanol and water, expressed as log P. Log P may be measured directly but more conveniently, it may be calculated from the structure of the molecule using one of the several commercially available software programs, such as ACD Software. The calculated value is abbreviated to clogP. Accordingly, preferred fragrances have a aqueous solubility below 20000 ppm, preferably below 10000 ppm, more preferably below 5000 ppm, most preferably below 2000 ppm. Thus, fragrances, such as phenylethylalcohol and diethylmalonate are preferably to be avoided. Furthermore, preferred fragrances have a clogP greater than 2, most preferred a clogP greater than 3. In a preferred embodiment the composition according to the present invention comprises about 0.1% to about 3%(w/w) fragrance. Most preferred are fragrance compositions having at least 80% (w/w) of fragrance with a clogP greater than 2.

Optionally, the hydrophobic phase may comprise a lipophilic dye, for example Puricolor® blue FBL5, Puricolor® blue FBL5 Puricolor® blue ABL9, Puricolor® green U3 or Puricolor® yellow AYE23 from Ciba.

Particularly preferred composition according to the present invention comprises from 2% to 15% (w/w) cationic softener; from 3% to 20% (w/w) ester oil; from 0.1% to 3% (w/w) fragrance; from 57% to 92.9% (w/w) water; and from 2% to 5% (w/w) other excipients.

Compositions according to the present invention may be used as fabric softeners. They may be added to the last rinse cycle in an amount of 35 ml to 150 ml per 4 kg of fabrics in general, or garments in particular. However, the amounts used is based upon the preferences of the user.

The invention is illustrated by the following examples.

EXAMPLE 1

A fabric softening composition of the present invention (herein after named as “bi-phase fabric softener”) was formulated as follows: % w/w Part A Rewoquat ® WE 18 di-(tallow carboxyethyl) 10.00 (Goldschmidt) hydroxy-ethyl methylammonium methosulfate Deionised Water 74.45 Calcium chloride 0.50 Myacide ® BT330 2-bromo-2-nitrophropane-1,3-diol 0.05 (Boots) Part B Isopropylmyristate 11.50 Isopar ® M 2.50 (Exxon) Fragrance 1.00 100.00

The water and the Rewoquat® WE 18 was heated separately to 50° C. While stirring the preheated water, one half of the Rewoquat® WE 18 (preheated to 50° C.) was added. Calcium chloride was added and then the remaining part of the Rewoquat® WE 18 while stirring the mixture. After cooling to room temperature under stirring, Myacide® BT330 was added. Finally, part B was added.

EXAMPLE 2

Fragrance evaluation: substantivity profile

The bi-phase fabric softener composition prepared according to example 1 was compared to a mono-phase fabric softener composition formulated as follows: % w/w Part A Deionised Water 81.75 MgCl₂ (saturated solution) 1.0 Part B Rewoquat ® WE 18 di-(tallow carboxyethyl) 13.0 (Goldschmidt) hydroxy-ethyl methylammonium methosulfate GenapolO100 Ethoxylated fatty alcohol 2.0 (Hoescht) C16-C18 10EO Antifoam 110A-EU silicone emulsion 1.0 (Dow Corning) Part C Dequest 2010 Hydroxyethyliden 1,1 0.2 (Monsanto) diphosphonic acid Proxel GXL Benzisothiazolinone sodium salt 0.02 (ICI) Bronidox L 5 bromo-5nitro-1,3 Dioxane 0.03 (Cognis) Fragrance 1.0 100.00

While stirring part A was heated to 65° C. Then part B (preheated to 65° C.) was added while stirring the mixture. After cooling to room temperature part C was added.

A European washing machine was loaded with 4 kg mixed fabrics, including cotton terry towels. In the last rinse cycle 35 grams of the fabric softener was added. The cotton terry towels were used to asses the performance of each fabric softener by an expert panel. TABLE 1 Bi-phase fabric mono-phase softener fabric softener dry towels 4 3 after 24 hours dry towels 4 2 after 5 days Evaluation scale: 5 = very strong 4 = strong 3 = moderate 2 = weak 1 = very weak

Panellists compared the strength of the fragrance on dry fabrics (Table 1). A much more improved fragrance strength and fragrance quality was achieved on dry fabrics with the bi-phase fabric softener composition prepared according to example 1 compared with the mono-phase fabric softener composition prepared according to the formulation above. Furthermore, the fragrance appears fresher using the bi-phase fabric softener.

EXAMPLE 3

Fragrance evaluation: Headspace

The cotton terry towels were washed according to the washing protocol of example 2. The towels were line dried and placed in a glass container 1 day/5 days after drying. During 15 minutes and an extraction flow of 30 ml/minute the headspace was collected. Then the samples were analysed by GC/MS. The results are shown in Table 2. TABLE 2 bi-phase fabric mono-phase softener fabric softener dry towels 489 ng/L 148 ng/L after 24 hours dry towels 394 ng/L  89 ng/L after 5 days

The bi-phase fabric softener delivered significantly more fragrance on the cotton terry towels.

EXAMPLE 4

Fragrance composition Ingredients % w/w Benzyl Acetate 4.0 Bornyl Acetate 4.0 Citronellyl Acetate 0.8 Menthanyl Acetate 2.0 PT Butylcyclohexyl Acetate 3.0 2-Propenyl Phenoxyacetate 3.6 Phenyl Ethyl Acetal 1.0 Verdyle Acetate ™ 10.0 Cyclamen Aldehyde Extra 2.5 Benzyl Benzoate 8.0 Citronellol 16.0 Coumarine pure Crist. 7.0 Diphenyl Oxyde 2.0 Geraniol 980 4.0 Isoraldeine ® 70 5.2 Lavandin Grosso Ess Orpur 2.0 Lilial 3.5 Linalool Synthetic 2.0 N-112 0.1 Peche Pure ® 0.1 Rosacetol ™ 7.5 Terpineol Pure 10.0 Vanilline 1.0 Virdine ® 0.7 100.0 

1. A fabric softener composition having an upper hydrophobic phase comprising a fragrance and a lower aqueous phase comprising a cationic softener wherein the pH value of the aqueous phase is below
 4. 2. A fabric softener composition according to claim 1 wherein the cationic softener is selected from the group of imidazolinium salts; amido amines; and ester-linked quaternary ammonium salts.
 3. A fabric softener composition according to claim 1 comprising up to 18% (w/w) of the cationic softener.
 4. A fabric softener composition according to claim 1 wherein the upper hydrophobic phase further comprises an oil is selected from the group consisting of hydrocarbon oil, silicone oil and ester oil.
 5. A fabric softener composition according to claim 4 wherein the oil has a hydrophilic-lipophilic balance less than
 5. 6. A fabric softener composition according to claim 1 wherein the upper hydrophobic phase further comprises an oil and wherein the fabric softener composition comprising from 1% to 50% (w/w) of the oil.
 7. A fabric softener composition according to claim 1 comprising from 2% to 18% (w/w) of cationic softener; from 1% to 50% (w/w) of oil; from 0.1% to 3% (w/w) of fragrance; and from 29% to 96.9% (w/w) of water.
 8. A fabric softener composition according to claim 1 wherein the fragrance is characterised by a clogP greater than
 2. 9. A fabric softener composition according to claim 1 adapted to disperse upon agitation, wherein the dispersion separates into a hydrophobic phase and an aqueous phase from about 10 to about 40 minutes after agitation.
 10. A method of prolonging the release of fragrance from a fabric up to 7 days comprising the step of treating a fabric with the fabric softener composition of claim
 1. 11. A method of prolonging the release of fragrance from a fabric up to 7 days comprising the step of treating a fabric with a fabric softener composition of claim 1 comprising: from 2% to 18% (w/w) of cationic softener; from 1% to 50% (w/w) of oil; from 0.1% to 3% (w/w) of fragrance; and from 29% to 96.9% (w/w) of water.
 12. A packaged fabric softener composition comprising of: (1) a package; (2) the fabric softener composition of claim
 1. 13. A packaged fabric softener composition of claim 12 comprising from 2% to 18% (w/w) of cationic softener; from 1% to 50% (w/w) of oil; from 0.1% to 3% (w/w) of fragrance; and from 29% to 96.9% (w/w) of water.
 14. A fabric softener composition according to claim 7 wherein the cationic softener is selected from the group of imidazolinium salts; amido amines; and ester-linked quaternary ammonium salts.
 15. A fabric softener composition according to claim 14 wherein the fragrance is characterised by a clogP greater than
 2. 16. A fabric softener composition according to claim 15 wherein the fragrance is characterised by a clogP greater than
 3. 17. A fabric softener composition according to claim 8 wherein the fragrance is characterised by a clogP greater than
 3. 